1. Field of the Invention
The invention relates in general to a backlight assembly, and more particularly to a backlight assembly whose optical films are held in the frame while the positioning flanges of the optical films are configured to abut against the edges of the frame in a number of directions.
2. Description of the Related Art
Featured by the advantages of having a light weight slim appearance, low power consumption and low radiation, the liquid crystal display (LCD) has gained a rapid advance in manufacturing technology and has been widely applied in electronic devices such as the personal digital assistant (PDA), notebook, digital still camera, digital video recorder, mobile phone, computer monitor and TV screen. Further, due to the long-term R&D investment and the adoption of large-scale manufacturing facilities, the quality of LCD device continues to improve while the price continues to decline. Consequently, the application of LCD is growing wider and wider. Since the display panel of an LCD is not self-luminous, a backlight assembly is required to provide necessary light for the display panel.
Referring to FIG. 1A, a diagram of a conventional backlight assembly is shown. In FIG. 1A, a backlight assembly 10 includes a frame 11, a light guide plate 12 and one or more optical films 13, wherein the bottom surface of the optical film 13 can be adhered to the top surface of the light guide plate 12 by means of adhesive tape (not shown in FIG. 1A). One lateral side of the optical film 13 has flanges 13a and 13b; wherein the flanges 13a and 13b respectively have openings 13c and 13d for respective bolts 15a and 15b to pass through. The optical film 13 is fixed to the frame 11 by inserting the bolts 15a and 15b through the openings 13c and 13d and screwing the bolts 15a and 15b into respective screw holes (not shown in FIG. 1A) in the frame 11.
Referring to FIG. 1B, another diagram of a conventional backlight assembly is shown. In FIG. 1B, a backlight assembly 20 includes a frame 21, a light guide plate (not shown in FIG. 1B) and one or more optical films 23, wherein the light guide plate 22 and the optical film 23 are both fixed within. The frame 21 has hooks 21a and 21b. One lateral side of the optical film 23 has flanges 23a and 23b, while the other lateral side of the optical film 23 has flanges 23e and 23f, wherein the flanges 23a and 23b. The flanges 23a and 23b have openings 23c and 23d for the respective bolts 25a and 25b to pass through. The flanges 23e and 23f respectively have openings 23g and 23h. The flanges 23e and 23f are fastened to the frame 21 by seating the openings 23g and 23h wherein the openings 23g and 23h can be hooked to the hooks around the respective hooks 21a and 21b. When the bolts 25a and 25b, inserted through the respective openings 23c and 23d, are screwed in respective screw holes in the frame 21 (not shown in FIG. 1B) and the openings 23g and 23h are hooked to the hooks 21a and 21b, the optical film 23 will be fixed to the frame 11.
It can be seen from the above disclosure that the conventional optical film is fixed to the frame by means of securing parts such as adhesive tape, bolts or hooks. Consequently, the additional securing parts increase the production cost, and are time-consuming to fasten. Moreover, since the conventional method according to FIG. 1A cannot fix the whole optical film precisely, the optical film is easily wrinkled, leading to a significant deterioration of luminance quality. According to the conventional method, the openings for securing the screws around the hooks are formed by punching holes in an optical film. However, the scraps of optical film obtained from punching cannot be recycled, and it is wasteful to throw away those scraps of optical film. Another problem is that the more flanges that are used the more likely light leakage will occur. Although the flanges 23e and 23f can be covered by shielding tape to reduce light leakage, additional tape costs are incurred. Furthermore, it is very difficult to separate the optical film from the light guide plate, because the optical film is tightly adhered to the light guide plate by adhesive tape.